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. 2023 Jan 19;15(3):532. doi: 10.3390/nu15030532

Table 1.

Effects of intermittent fasting on breast cancer patients.

Author Year Population Fasting Regimen Results Type of Study
Kleckner et al. [17] 2021 21 (20 breast cancer survivors) Women followed a 2-week 14: 10 h TRF dietary regimen (this dietary pattern included 14 h of fasting within the same day) with no inclusion of a control group in the study. Fatigue scores improved in 2 weeks 5.3 ± 8.1 points on the FACIT-F fatigue subscale (p < 0.001, effect size (ES) = 0.55), 30.6 ± 35.9 points for the FACIT-F total score (p < 0.001, ES = 0.50), and 1.0 ± 1.7 points on the BFI (p < 0.001, ES =−0.58). Clinical trial
De Groot et al. [26] 2020 131 (HER-2 negative stage II/III breast cancer) Fasting mimicking diet 3 days before and during neoadjuvant chemotherapy.

  1. There were no differences in Grade 3/4 toxicity during chemotherapy between participants in the fasting and usual care groups.

  2. Miller–Payne scores 4/5 pathologic response is more common in FMD.

  3. Patients who followed FMD more closely had a more significant percentage of Miller–Payne 4/5 scores.

 Randomized, controlled, observer-blind study
Zorn et al. [25] 2020 30 (cancer patients) 96 h fasting for half of scheduled chemotherapy cycles, followed by a regular diet for the remaining cycles.

  1. Fasting is linked to increased serum ketone and lower insulin and IGF-1 level concentrations.

  2. The frequency and severity score of stomatitis, headaches, weakness, and the total toxicities’ score were significantly reduced (−10.36 ± 4.44; 95% CI, 19.22–(−1.50); p = 0.023) in the STF group.

  3. Significantly fewer chemotherapy postponements post-STF were observed, reflecting improved tolerance of chemotherapy.

 Controlled cross-over pilot study
Mas et al. [21] 2019 16 (breast cancer) Participants were not instructed according to a specific dietary regimen, but rather, followed nutrition advice from healthcare practitioners. Patients fasted in order to alleviate chemotherapeutic adverse effects and treatment-induced anxiety. The authors reported that fasting improved nausea and vomiting, as well as appetite, satiation, and fatigue between chemotherapy sessions. Qualitative study
Bauersfeld et al. [19] 2018 34 (breast and ovarian cancer) Patients were randomly assigned to either a short-term fasting diet followed by a normal caloric diet or a normal caloric diet followed by a short-term fasting diet in the first half of chemotherapy. Within 8 h after treatment, patients on the fasting diet reported improved quality of life and tiredness. Randomized cross-over pilot study
Dorff et al. [28] 2016 5 (BC female) Fasting for 24 h, 48 h, or 72 h before chemotherapy.

  1. Fasting is doable and safe.

  2. Fasting cohorts had lower incidences of neutropenia and neuropathy.

  3. The COMET assay indicated reduced DNA damage in leukocytes from subjects who fasted for ≥48 h (p = 0.08).

  4. IGF-1 levels decreased by 30, 33, and 8% in the 24, 48, and 72 h fasting cohorts, respectively, after the first fasting period.

 Cohort
Marinac et al. [23] 2015 2413 (BC female) Dietary recalls were utilized to calculate the length of time spent fasting at night. Fasting for less than 13 h per night is connected with a 36% greater risk of the recurrence of breast cancer when compared to individuals fasting for ≥13 h per night. Cohort
De Groot et al. [27] 2015 13 (HER2-negative, Stages II/III) Before and after chemotherapy, patients were randomly assigned to either a 24 h fast or a diet that followed appropriate dietary standards.

  1. Fasting was well tolerated.

  2. Fasting may aid in the healing of DNA damage caused by neoadjuvant TAC regimen (docetaxel/doxorubicin/cyclophosphamid).

 Randomized pilot study
Badar et al. [20] 2014 4 (BC patients at Stages IIB/IIIB/IV) Ramadan-fasting patients previously received chemotherapy (20 min after sunset) and, then, continued their fasting routine (daily from dawn to sunset and ate from sunset to dawn) for the rest of the month.

  1. 12.5% of patients noted nausea improvement during fasting.

  2. 50% of patients reported fatigue improvement during fasting.

  3. 62.5% of patients felt better while fasting.

 Non-randomized, cross-over, pilot study
Safdie et al. [22] 2009 4 (breast cancer) Fasting before 48–140 h or fasting after 5–56 h of treatment.

  1. Fasting is safe and well tolerated.

  2. Fasting has been linked to decreased tiredness, weakness, and gastrointestinal side-effects.

 Case series